1. Field of the Invention
The present invention relates to a method and apparatus for braking a washing machine, more particularly, to a method and apparatus for braking a washing tub and a dehydrating tub of a washing machine by simultaneously or selectively applying a mechanical band brake and an electrical brake, which results in an enhanced braking reliability and braking efficiency.
2. Description of the Related Art
Typically, a washing machine washes clothes by current of water mixed with detergent in a washing tub, and dehydrates the washed and wet clothes in a dehydrating tub by a centrifugal separating force. The washing machines may be divided into belt-driving washing machines and direct-coupled washing machines according to the manner of driving them.
In the belt-driving washing machine, a washing tub and a dehydrating tub are driven by a driving force transmitted from a driving motor through a belt and a shaft. The dehydrating tub is braked by a band brake of the shaft.
Different from the belt-driving washing machine, the direct-coupled washing machine does not utilize a belt. In the direct-coupled washing machine, a shaft of a driving motor is arranged on a straight line with central shafts of a washing tub and a dehydrating tub. The washing tub and the dehydrating tub are directly driven by the driving motor. The dehydrating tub is braked in such a manner that rotations of the dehydrating tub is stopped by an electric power of the driving motor.
The belt-driving washing machine suffers a disadvantage that it may be vibrated and oscillated during operation because a rotary shaft of the driving motor and a rotary shaft of the washing tub are not arranged on a straight line from the structural characteristics thereof. On the other hand, a shaft of a driving motor, central shafts of a washing tub and a dehydrating tub of the direct-coupled washing machine are arranged on a straight line. Accordingly, such vibration and oscillation related to the belt-driving washing machine may not occur in the direct-coupled washing machine. This results in an increased adoption of the direct-coupled washing machines.
However, the direct-coupled washing machine also suffers a disadvantage that the driving motor thereof should have a large capacity to afford the load during washing and dehydrating processes. To overcome the disadvantage, an indirect/direct coupled washing machine is provided. The indirect/direct coupled washing machine further includes predetermined reduction gears for driving a washing tub, whereby, the capacity of the driving motor that is required for the above mentioned washing machines can be reduced according to the reduction gear ratio.
Though the capacity of the driving motor can be reduced by further including the reduction gears, the indirect/direct coupled washing machine still suffers a disadvantage that, as the capacity of the motor is reduced, it is impossible to stop the dehydrating tub using an electrical brake in a safe braking time corresponding to a safe standard of a washing machine.